Light Emitting Diode (LED) device and similar semiconductor devices are typically provided with a radiation substrate (a heat sink) for externally radiating heat generated when a semiconductor element is driven.
For example, Patent Literature 1 (Japanese Patent Laying-Open No. 6-268115) discloses that a Cu plate formed by rolling to have a diameter of 200 mm and a thickness of 0.465 mm and an Mo plate having the same diameter as the Cu plate and a thickness of 0.090 mm are prepared and the Cu plate, then the Mo plate and then another Cu plate are successively disposed and hot pressed to provide a 1.02 mm thick Cu/Mo/Cu clad material, which is in turn used as a radiation substrate of a semiconductor device (see Patent Literature 1, paragraphs [0034]-[0049] for example).
Furthermore, Patent Literature 1 also describes that a similar method with Mo replaced with W can also be employed to obtain a significantly reliable clad material (see Patent Literature 1, paragraph [0033]).